一個尋常的操作證實了alter system 預設範圍為both

snowdba發表於2014-12-24

今天在設定 alter system set log_checkpoints_to_alert=true; 這個引數時，第一時間在alert日誌中看到了該引數的修改記錄，預設範圍就是both。雖然知道這個知識點，當該引數設定成功後在tail alert日誌的視窗第一時間看到這個輸出還是挺有意思的。

SYS@OCM10G >show parameter log_checkpoint

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
log_checkpoint_interval              integer     0
log_checkpoint_timeout               integer     1800
log_checkpoints_to_alert             boolean     FALSE

SYS@OCM10G >alter system set log_checkpoints_to_alert=true;

System altered.

tail 日誌片段
Completed: ALTER DATABASE OPEN
Tue Dec 23 21:48:33 2014
db_recovery_file_dest_size of 200 MB is 34.10% used. This is a
user-specified limit on the amount of space that will be used by this
database for recovery-related files, and does not reflect the amount of
space available in the underlying filesystem or ASM diskgroup.
Tue Dec 23 21:54:31 2014
Shutting down archive processes
Tue Dec 23 21:54:36 2014
ARCH shutting down
ARC2: Archival stoppedWed Dec 24 20:53:56 2014
MMNL absent for 81271 secs; Foregrounds taking over
Wed Dec 24 20:55:12 2014
ALTER SYSTEM SET log_checkpoints_to_alert=TRUE SCOPE=BOTH;


下圖是官方文件對該引數的解釋，截圖做個紀念

LOG_CHECKPOINTS_TO_ALERT

Property Description
Parameter type Boolean
Default value false
Modifiable ALTER SYSTEM
Range of values true | false
Basic No
LOG_CHECKPOINTS_TO_ALERT lets you log your checkpoints to the alert file. Doing so is useful for determining whether checkpoints are occurring at the desired frequency.
該引數用來檢測checkpoints的發生頻率

來自 “ ITPUB部落格 ” ，連結：http://blog.itpub.net/29047826/viewspace-1379043/，如需轉載，請註明出處，否則將追究法律責任。

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